Ultra-processed food intake wasn’t linked to colorectal cancer, but the specific foods you choose may increase your risk.
Reviewed by Dietitian Jessica Ball, M.S., RD
Key Points
- A new study investigated the connection between ultra-processed foods and colon cancer.
- Whole grains and dairy from ultra-processed foods may lower colorectal cancer risk.
- Processed meat intake was associated with a higher colorectal cancer risk.
Ultra-processed foods make up more than half of the calories U.S. adults eat. But “ultra-processed” includes everything from hot dogs to whole-wheat bread, which may help explain why research linking these foods to colorectal cancer has been inconsistent. However, new research suggests that what’s in ultra-processed food may impact your colon cancer risk more than how processed it is.
Published in PLOS Medicinethe study found no link between total ultra-processed food intake and colorectal cancer risk. However, whole grains and dairy from ultra-processed sources were associated with lower risk, while eating meat from ultra-processed sources was linked to higher risk. Here’s what you need to know.
How Was the Study Conducted?
Researchers analyzed 461,682 U.S. adults in the NIH-AARP Diet and Health Study. Participants were between the ages of 50 and 71 and cancer-free when they enrolled in 1995 or 1996. They completed a 124-item food frequency questionnaire, and researchers classified each food using the Nova system, which sorts foods by degree of processing. Ultra-processed foods made up a median of 43% of the participants’ daily calories.
Participants were followed through 2018, for a median of 18.8 years, during which time 10,075 were diagnosed with colorectal cancer. The analysis adjusted for factors including age, sex, race and ethnicity, education, physical activity, smoking and alcohol intake.
What Did the Study Find?
People in the highest fifth of ultra-processed food intake did not have a higher risk of colorectal cancer compared to those in the lowest fifth. However, this changed when researchers looked at what those foods contained. Here’s how the findings broke down:
- Whole Grains: Each additional daily serving from ultra-processed sources, such as bread and breakfast cereal, was linked to a 13% lower risk of colorectal cancer. Fiber intake was also linked to lower risk.
- Dairy: Each additional daily serving was linked to 25% lower risk of colorectal cancer when it came from ultra-processed sources and 10% lower risk from other sources.
- Meat: Each additional daily serving from ultra-processed sources was linked to 8% higher risk, plus a 4% higher risk from other sources. Reconstituted meat and fish products were also associated with higher risk.
Servings were measured per 1,000 calories eaten. Roughly 83% of the whole grains and 74% of the processed meat in this cohort’s diets came from ultra-processed foods, so protective and harmful foods sat in the same category and may have offset each other. Poor overall diet quality was also linked to higher risk, regardless of how much ultra-processed food people ate.
Limitations
This was an observational study, so it can’t prove cause and effect. Diet was measured only once, and it was done with a questionnaire that wasn’t designed to gauge food processing. Participants were older and mostly white, so the findings may not apply to younger or more diverse groups, and the authors call the food-group analyses exploratory. The researchers also didn’t assess food additives.
How Does This Apply to Real Life?
The study’s authors note that their findings align with advice to eat more whole grains, fiber and dairy and to avoid processed meat for colorectal cancer prevention.
Here are a few helpful tips:
- Choose whole grains. Opt for breads and cereals where a whole grain is the first ingredient, such as oats or brown rice.
- Include dairy. Milk and yogurt are easy options. The study linked higher calcium intake to lower colorectal cancer risk, but it can’t say whether non-dairy calcium sources offer the same benefit, so ask a dietitian if you avoid dairy.
- Swap out processed meat. Try beans, lentils, tofu or leftover roast chicken in place of red meat options like deli meat, hot dogs and bacon.
Our Expert Take
A study of more than 460,000 U.S. adults found no link between total ultra-processed food intake and colorectal cancer risk, but it did find that the ingredients in certain processed foods can increase your risk. Whole grains and dairy were associated with lower risk, while meat from ultra-processed sources was linked to higher risk. The takeaway isn’t that you should eat ultra-processed foods, but that you should pay attention to what’s inside the processed foods you’re eating. Aim to eat more whole grains and dairy and cut back on processed meat.